Osaka had to work for nearly two hours on Rod Laver Arena to subdue the gritty Sevastova 4-6, 6-3, 6-4 in a fourth-round match studded by service breaks. She'll next play sixth-seeded Elina Svitolina, who had a 6-2, 1-6, 6-1 win over 2017 US Open finalist Madison Keys.
Osaka won a tight three-setter when she met Sevastova at the Brisbane International in the first week of the season.
Sevastova grabbed the lead in the opening set on Monday, and clinched it with a deft drop shot that forced Osaka to fly a forehand over the baseline.
Osaka had to stave off two break points in the third game of the second to edge ahead.
The fourth-seeded Osaka grew in confidence from the narrow escape and lifted her tempo and shot-making consistency, grabbing the crucial service break in the sixth game.
Serving to level the match, Osaka fended off a break-back point with a brilliant forehand volley after a long, tense baseline rally. Two points later, the match was heading into the deciding set.
Osaka broke serve to open third set to maintain the momentum.
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